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The Fe (III)/Fe(II) redox couple as a probe of immobilized tobacco peroxidase : Effect of the immobilization protocol

Olloqui-Sariego, José Luis; Zakharova, Galina S.; Poloznikov, Andrey A.; Calvente, Juan José; Hushpulian, Dmitry M.; Gorton, Lo LU and Andreu, Rafael (2019) In Electrochimica Acta 299. p.55-61
Abstract

Non-turnover voltammetry is a sensitive tool to characterize the electrochemical properties of redox proteins. However, the catalytically competent oxidation states of most peroxidases do not display the required electrochemical reversibility. In this report, we circumvent this limitation and exploit the voltammetric response associated with the Fe(III)/Fe(II) redox couple of tobacco peroxidase to probe the energetics and electronic connectivity of the heme pocket. We have applied this approach to rationalize the previously reported influence of the immobilization protocol on the electrocatalytic activity of tobacco peroxidase. To decouple proton and electron transfer steps, measurements have been carried out over the 3 ≤ pH ≤ 9 range... (More)

Non-turnover voltammetry is a sensitive tool to characterize the electrochemical properties of redox proteins. However, the catalytically competent oxidation states of most peroxidases do not display the required electrochemical reversibility. In this report, we circumvent this limitation and exploit the voltammetric response associated with the Fe(III)/Fe(II) redox couple of tobacco peroxidase to probe the energetics and electronic connectivity of the heme pocket. We have applied this approach to rationalize the previously reported influence of the immobilization protocol on the electrocatalytic activity of tobacco peroxidase. To decouple proton and electron transfer steps, measurements have been carried out over the 3 ≤ pH ≤ 9 range and a 1e/2H+ ladder scheme has been adopted for their analysis. At each pH, thermodynamic and kinetic parameters associated with the Fe(III)/Fe(II) redox conversion were determined as a function of temperature in the 0-30 °C range. Reduction entropies and reorganization energies displayed different values for covalently immobilized and physisorbed enzymes, pointing to a larger involvement of the solvent in the last case. These findings, together with a larger electronic coupling between the prosthetic group and the electrode, are indicative of a partial denaturation of the physisorbed enzymes as the origin of their lower electrocatalytic activity.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fe(III)/Fe(II) couple, Immobilization protocol, Proton coupled electron transfer, Thermodynamics and kinetics, Tobacco peroxidase
in
Electrochimica Acta
volume
299
pages
7 pages
publisher
Pergamon
external identifiers
  • scopus:85060875854
ISSN
0013-4686
DOI
10.1016/j.electacta.2018.12.153
language
English
LU publication?
yes
id
75e1944c-ed8f-4604-9307-cea4e9ff437d
date added to LUP
2019-02-11 11:37:41
date last changed
2019-02-11 11:37:41
@article{75e1944c-ed8f-4604-9307-cea4e9ff437d,
  abstract     = {<p>Non-turnover voltammetry is a sensitive tool to characterize the electrochemical properties of redox proteins. However, the catalytically competent oxidation states of most peroxidases do not display the required electrochemical reversibility. In this report, we circumvent this limitation and exploit the voltammetric response associated with the Fe(III)/Fe(II) redox couple of tobacco peroxidase to probe the energetics and electronic connectivity of the heme pocket. We have applied this approach to rationalize the previously reported influence of the immobilization protocol on the electrocatalytic activity of tobacco peroxidase. To decouple proton and electron transfer steps, measurements have been carried out over the 3 ≤ pH ≤ 9 range and a 1e<sup>−</sup>/2H<sup>+</sup> ladder scheme has been adopted for their analysis. At each pH, thermodynamic and kinetic parameters associated with the Fe(III)/Fe(II) redox conversion were determined as a function of temperature in the 0-30 °C range. Reduction entropies and reorganization energies displayed different values for covalently immobilized and physisorbed enzymes, pointing to a larger involvement of the solvent in the last case. These findings, together with a larger electronic coupling between the prosthetic group and the electrode, are indicative of a partial denaturation of the physisorbed enzymes as the origin of their lower electrocatalytic activity.</p>},
  author       = {Olloqui-Sariego, José Luis and Zakharova, Galina S. and Poloznikov, Andrey A. and Calvente, Juan José and Hushpulian, Dmitry M. and Gorton, Lo and Andreu, Rafael},
  issn         = {0013-4686},
  keyword      = {Fe(III)/Fe(II) couple,Immobilization protocol,Proton coupled electron transfer,Thermodynamics and kinetics,Tobacco peroxidase},
  language     = {eng},
  pages        = {55--61},
  publisher    = {Pergamon},
  series       = {Electrochimica Acta},
  title        = {The Fe (III)/Fe(II) redox couple as a probe of immobilized tobacco peroxidase : Effect of the immobilization protocol},
  url          = {http://dx.doi.org/10.1016/j.electacta.2018.12.153},
  volume       = {299},
  year         = {2019},
}